Cheapest return flights from Ontario to San Francisco in October from $97

AirHint found the following cheapest return flights from Ontario (ONT) to San Francisco (SFO) in October 2025 (see full year).

Return flights

01 Oct - 04 Oct United direct
03 Oct - 05 Oct Frontier Airlines direct
16 Oct - 20 Oct Frontier Airlines direct
21 Oct - 28 Oct Frontier Airlines
08 Oct - 14 Oct Frontier Airlines
11 Oct - 18 Oct Frontier Airlines
07 Oct - 14 Oct Frontier Airlines
02 Oct - 08 Oct Frontier Airlines
14 Oct - 21 Oct Frontier Airlines
30 Oct - 15 Nov Frontier Airlines
06 Oct - 09 Oct Frontier Airlines direct
30 Oct - 03 Nov Frontier Airlines direct
30 Oct - 02 Nov Frontier Airlines
30 Oct - 02 Nov Frontier Airlines direct
31 Oct - 01 Nov Southwest Airlines
31 Oct - 29 Nov Frontier Airlines

Also check the deals for one-way flights from Ontario to San Francisco in October.

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The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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